Temperature-responsive system for regulating the fuel mixture in air-cooled internal combustion engines

ABSTRACT

In the cooling circuit of an air-cooled internal combustion engine there is disposed a temperature responsive member which moves a lever connected to a fuel quantity control member of a fuel injection pump. The transmission of motion from said lever to said control member is affected by a contoured control edge or cam track provided in the former.

United States Patent 1191 Knapp 1 TEMPERATURE-RESPONSIVE SYSTEM FOR REGULATING THE FUEL MIXTURE IN AIR-COOLED INTERNAL COMBUSTION ENGINES [76] Inventor: Heinrich Knapp, Hummelbergweg 24, Leonberg-Silberberg, Germany [22] Filed: Sept. 28, 1970 [21 1 Appl. No.: 76,036

[30] Foreign Application Priority Data Jan. 29, 1970 Germany ..P 20 ()3 927.4

[521 US. Cl. ....l23/l40 MC, 123/140 R, 123/1791, 123/179 (1,123/119 F [51] Int. Cl. ..F02Cl 1/04, F02n 17/00 [58] Field of Search ..123/l40 MC, 140 R, 123/140 EC, 179 L, 179 G, 119 F; 73/3635,

[56] References Cited UNITED STATES PATENTS 2,01 1,899 8/1935 Jorgensen. "73/3626 2,100,709 11/1937 Crone .1 1,703,235 2/1929 Heath ..73/362.6

1451 Apr. 17, 1973 3,177,720 4/1965 Metheny ..73/362.6 3,401,666 9/1968 Munroe ,...73/362.6 1,243,112 10/1917 Sandvoss ..73/362.6 2,852,011 9/1958 Pringham.... .....123/140 MC 2,881,748 4/1959 Foddy v...123/140 MC 2,465,090 12/1960 Claire 1. 123/179 1. 3,004,123 10 1961 Cannon... ....73/363.1 3,107,552 10/1963 Lingnau 73/3635 3,344,672 10 1967 Lingnau .73/3635 3,577,972 5/1971 Gargea 1 23/140 MC FORElGN PATENTS OR APPLICATIONS 1,171,201 5/1964 Germelny ..123/14(l MC Primary Examiner-Laurence M. Goodridge Assistant ExaminerRonald B. Cox

Attorney-Edwin E. Greigg 1 57 ABSTRACT In the cooling circuit of an air-cooled internal combustion engine there is disposed a temperature responsive member which moves a lever connected to a fuel quantity control member of a fuel injection pump. The transmission of motion from said lever to said control member is affected by a contoured control edge or cam track provided in the former.

3 Claims, 3 Drawing Figures TEMPERATURE-RESPONSIVE SYSTEM FOR REGULA'IING THE FUEL MIXTURE IN AIR- COOLED INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION The invention relates to a regulating system for controlling the air-fuel mixture in externally ignited internal combustion engines. The system is of the type that includes a preferably rpm-dependent setting member, the setting motions of which may be transmitted by means of a first and a second intermediate lever to a fuel quantity'control member. The pivotal point of the second intermediate lever is disposed on a correcting lever which'is provided with a contoured edge and which is engaged by setting members movable dependent upon operational magnitudes of the engine. One of the last-named setting members is a temperature sensor responsive to the temperature of the engine coolant.

In regulating systems of the afore-outlined type it is required that, in addition to other operational magnitudes, the intake air temperature and the cylinder head temperature of the engine also be taken into account for the formationlof fuel mixture and it is further required to vary the quantities delivered by the fuel injection system of the engine as a function of the aforenoted temperatures. i

In a known regulating system of the aforenoted type (as described, for example, in German Pat. No. 1,171,201), the temperature-dependent change of the deliveredfuel quantities is controlledby a temperature sensitive member exposed to the circulating water coolant in a water-cooled engine. Such variations in the fuel quantity, however, serve only forcorrecting an engine operation in a hot condition, wherein the supplementary fuel quantities required for a satisfactory operation of a cold engine arecontinuously decreased up to a coolant temperature of approximately 35 C. Above this temperature, the delivered fuel quantities are no longer affected by the temperature sensitive member.

Since water-cooled engines are so-called temperature-stabilized engines, that is, the circulation of the water coolant is adjusted to the operational condition of the engine by control elements, the temperature of the cylinder head is substantiallyconstant andrthe limit values regarding the harmful components of the exhaust gases (the so-called Californiatest) may be maintained by an appropriate setting of thecorrecting members. The temperatures of the inlet channel and the cylinder head determining the formation of the fuel mixture, are thus wellrepresented by the temperature ofthe water coolant.

In air-cooled engines which are nottemperature-stabilized and in which the flow rate of cooling air is rpmdependent, butnot controlled, the temperature of the cylinder head depends very closely from the operational condition of the engine and from the temperature ofthe air. Thus, an exhaust gas composition which does not exceed maximum permissible values :is difficult to obtain, particularly in city driving.

It has already been proposed to install in the wall of the cylinder head ofthe engine and in the suction tube, electric temperature sensors which generate control signals for the setting members; In fuel injection systems that have a mechanical regulating system, such a solution, however, is complex andexpensive.

It has further been proposed to utilize the temperature of the engine oil for control purposes in a manner similar to the temperature of the water coolant. This, however, cannot be materialized in a satisfactory manner, since the oil reacts very sluggishly to temperature changes.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention to provide an improved regulating system of the aforenoted type which in air-cooled, not temperature-stabilized engines adjusts the fuel quantities delivered by the fuel injection system during hot engine operation and adjoining operational ranges in such a manner to the temperatures of intake air and cylinder head that a very satisfactory engine operation is achieved and the limit values for the proportions of harmful components in the exhaust gas are not exceeded.

Briefly stated, according to the invention, there is provided a temperature sensing member which is formed preferably of a great number of heat expandable elements of large surface and which is exposed to at least one part of the cooling air heated by the engine cylinders of an air-cooled, not temperature-stabilized engine. Further, the contoured control edge ofthe correcting lever has a first, very steep portion for effecting correction of the injected fuel quantities during hot engine operation and a second, substantially flatter portion for the correction of the injected fuel quantities dependent from the operational temperature ofthe engine. Itis particularly advantageous to use a single temperature sensingmember.

The invention will be better understood as well as further objects and advantages of the invention will become more apparent from the ensuring detailed specification ofa preferred, although exemplary embodiment taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic view ofa regulating system incorporating the invention;

FIG. 2 is an enlarged, axial sectional view of FIG. 1, and

FIG. 3 is a diagram illustrating the values of the delivered fuel quantities v. temperature, as controlled by a regulating system according to FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. 1, to the drive shaft 10 of an only schematically indicated fuel injection pump 11 associated with an air-cooled not temperature-stabilized Otto-engine, there is mounted a centrifugal governor 12, the weights 13 of which displace, in case of a change in the rpm, a three-dimensional cam 14 which is movable as an rpm-dependent setting member against the force of a spring 15. The three-dimensional cam 14 may be rotated by an actuating arm 16 through linkage 17 in such a manner that, dependent upon the position of the actuating arm 16, a different cam track of the cam face is aligned with a follower roller 20 carried by a bell crank-type first intermediate lever 21. The actuating arm 16 is connected in a known manner (not shown) with the accelerator pedal and with the but terfly throttle of the engine.

a part of Rpm-dependent linear displacements, as well as rotational motions (caused by actuating arm 16) executed by the three-dimensional cam 14 result in a pivotal motion of the first intermediate lever 21 as a function of the shape of the momentary cam track 22 aligned with the follower roller 20. The motion of lever 21 is transmitted to a second intermediate lever 25 which has a pivot pin 26 supported on a correcting lever 27. The latter carries at one end 28 a contoured control edge 29. The latter slides, during motions of the correcting lever 27, along a pin 30 fixedly attached to a schemati cally indicated housing 34 of the regulating system 35. The other end 31 of the correcting lever 27 is articulatedly connected by means of a shackle 32 to a bracket 33 rigidly secured to housing 34.

The second intermediate lever 25 has, at one end, a slot 36 into which extends a pin 37 of the first intermediate lever 21. At its other end, the lever 21 has a second slot 38 in which there is guided a pin 41 fixedly secured to a fuel quantity control member of the fuel injection pump 11. Thus, motions of the bell crank lever 21 or the pin 26 of the second intermediate lever 25 are transmitted to the fuel quantity control member 40.

A pressure bar 43 engages the one end 42 the correcting lever 27 between the pivot 26 and the shackle 32, while the other end 44 of the pressure bar 43 is in contact with a lever 45. The sharp ends 42 and 44 of the bar 43 are received in notches 46 and 47 provided, respectively, in the correcting lever 27 and in the lever 45. The pressure bar 43 is maintained in its position by means of a tension spring 48 which, by virtue of its oblique position, simultaneously presses the contoured control edge 29 of the correcting lever 27 to the stationary pin 30 so that all play is eliminated. The lever transmits the setting motion of two setting members 49 and 50 (responsive to operational magnitudes ofthe engine) to the pressure bar 43, which, in turn, displaces the correcting lever 27 against the force of the spring 48 as soon as at least one of said operational magnitude varies.

The setting member 49 is a height correcting device and responds to the ambient air pressure surrounding the engine. The setting member 50 is a temperature sensing member which is affected by the temperature of the cooling air and the setting motions of which are transmitted by a rod 51 through the lever 45 and the pressure bar 43 to the correcting lever 27.

Turning now to FIG. 2, the temperature sensing member 50 comprises a housing 52 which is affixed to the housing 34 of the regulating system 35 and which has two coupling nipples 53 and 54, constituting, respectively, an inlet and an outlet for the cooling air. One part of the cooling air that is heated by the engine cylinder and used for heating the passenger compart ment of the vehicle, is branched off in a manner not shown and is directed, through a hose 55 and the coupling nipple 53, to the temperature sensing member 50 and is taken out therefrom through the coupling nipple 54 and an adjoining hose 56. Due to the fact that the engine is not temperature-stabilized, i.e., the flow rate of air is not regulated, but varies in an rpm-dependent manner according to the delivery characteristics of the fan, the temperature of the cooling air is a measure of the temperature of the engine cylinders. In

order to sense the temperature variations of the cooling air in a sufficiently rapid manner even at low rpms and thus at low air flow rates, the temperature sensing member 50 has, as heat expandable elements, a series of disc-like bimetallic plates 57 arranged in pairs, the outer surface of which is exposed to the flow of the cooling air. The bimetallic plate pairs 57 have a central bore 58 by means of which they are inserted and thus stacked on the actuating rod 51.

The actuating rod 51 is held in the housing 52 and has, at one end, a collar 59 formed by a snap ring on which the stack of plates 57 rests. As a second support for the plates 57, there is provided a spring seat disc 61 which is pressed against a shoulder 63 of housing 52 by a take-up spring 62 forming a resilient abutment for the stack of plates 57. The spring 62 is received in a cavity 64 of a cap 65 closing the housing 52. The cap 65 further carries a bearing member 66 in which one end of the actuator rod 51 is received. Between the bimetal plate 57 that is disposed closest to the spring seat disc 61 and the latter there are inserted compensating discs 67 with the aid of which a basic position of the temperature sensing member 50 may be set. This position is characterized by the distance a which, in turn, represents the extent of protrusion ofthe actuating rod 51. There is further provided a compression spring 68 (FIG. 1) engaging the housing 34 and urging the lever 45 continuously against the temperature sensing member 50.

Turning once again to FIG. 1, the contoured control edge 29 is kinked and has a steep portion 29a and a flat portion 29b. Edge portion 29a controls the fuel quantities delivered to the engine in a cold condition of the engine up to a cooling air temperature of approximately 35 C. The edge portion 29b controls the operational range between temperatures of 35 and C. The edge portion 29b terminates in a rigid stop (formed here as the end ofa slot) for reasons to become clear as the specification progresses. During idling operation, the contoured control edge 29 effects a course of delivered fuel quantities as indicated in the diagram according to FIG. 3. In this figure, the abscissa indicates the temperature T of the cooling air, whereas the ordinate is the fuel quantity 0 expressed in mm /stroke. At lO C, the fuel quantity delivered is A, whereas the kink point of the curve (at 35 C) is indicated at B, and the terminus of the control curve at 80 C is indicated at C. If the cooling air temperatures are over 80 C, the delivered fuel quantities are no longer affected by the temperature sensing member 50.

OPERATION OF THE EMBODIMENT The operation of the individual structural groups of the regulating system has already been described hereinabove and in the description that follows, emphasis is placed on the mode of operation of the temperature sensing member 50. In the example described, the engine starts at low temperature. In order to simplify the operational description, it is further assumed that the actuating arm 16 is in an idling position.

In case of a cooling air (i.e., ambient air) temperature under 35 C, the correcting lever 27 is in a position as shown in FIG. 1. This position corresponds, for example, in case of an air temperature T ofl0 C to a fuel quantity A in FIG. 3.

After starting the engine, the temperature of the cylinder head increases, and the cooling air is warmed accordingly. One part of the circulating cooling air is, through the flexible conduit 55, directed to the inside of the housing 52 of the temperature sensing member 50. By virtue of their large surface, the bimetallic plates 57 very rapidly assume themselves these higher temperatures; they expand, and pressing on the collar 59 of the actuating bar 51, displace the same against the force of the spring 68. The actuating rod 51 transmits its displacement to the lever 45 which, in turn, through the pressure bar 43, exerts a force on the correcting lever 27. As a result, the latter moves downward,

- whereby the contoured control edge 29 slides along the stationary camming pin 30. At the same time, the pin 26 of the second intermediate lever 25 is displaced downwardly and to the right causing, through the pin 41, the fuel quantity control rod 40 of the fuel injection pump 11 to be displaced in the direction. of a smaller fuel quantity delivery. By virtue of the slots 36 and 38, provided in the second intermediate lever 25, the downward motion of the latter-causes no change in the position of the fuel quantity control member 40. Solely the slope of the control edge 29 is a measure for the change of the fuel quantity control member and thus the delivered fuel quantities.

Up to approximately 35 C, the correcting lever 27 follows the portion 294 of the contoured control edge 29. As the kink point 290 reaches the pin 30, the fuel quantity control rod, 40 has been displaced to such an extent that the delivered fuel quantity Qcorresponds to the magnitude B inFIG. 3. i

As the temperature of the cooling airfurther increases, the bimetallic plates 57 continue their approximately linear expansion, but, by. virtue ofithe relatively flat portion 29b of, the contoured control edge 29, the decrease of the delivered fuel quantities occurs ata smaller rate. Up to 80? C,,the. delivered fuel quantities Q follow the curve portionB C ofFJG. 3. At 80 C, the contoured control edge 29terminates andlthe pin 30 is stopped at the end of the portion 29b. The delivered fuel quantities at that point correspond to the magnitude C in FIG. 3. Further temperature increases do not result in any further control motions since the bimetallic plates57 now displacethe spring seat disc 6l against the force of the take-up springt62. By virtue of its compression it is prevented that unpermissibly high forces are introduced into thelregulating system.

It is thusiseen that bymeansof the portion 29a of the contoured control edge the hot engine run is controlled, while portion 29b provides that .at different temperatures of the cylinder head. inthe load range, the delivered fuel quantities'areso adjustedthat no unpermissibly high proportions of harmful pollutants will appear in the exhaust gases.

What is claimed is:

1. In a regulating system for controlling the fuel mixture delivered by a fuel injection system to an externally ignited, air-cooled. internal combustion engine, said regulating system is of the type that includes (a) an rpm-responsive. setting; member, .(b) a first intermediate lever to which the motions of saidrp'm-responsive setting member are transmitted, .(c) a second intermediate lever connected to said first intermediate lever and to a fuel quantity control member. to transmit thereto displacements of said rpm-responsive setting member and (d) a correcting lever to which said second intermediate lever is pivotally secured, the improvement comprising,

A. an expandable temperature sensing member constituting an additional setting member and disposed within the cooling circuit of said aircooled engine to respond to the temperatures of the cooling air, said temperature sensing member having a first end and a second end,

rod means attached to said first end of said temperature sensing member, said rod means being displaced in a first direction by said temperature sensing member by virtue of its expansion caused by an increase in the temperature of said cooling air,

C. first spring means constituting a resilient abutment for said temperature sensing member and being in engagement with said second end thereof, said first spring means opposing the expansion of said temperature sensing member,

D. second spring means operatively connected to said rod means for urging the latter in a second direction opposite to said first direction; said second spring means being weaker than said first spring means for allowing said rod means to move insaid first direction in response to the expansion of said temperature sensing member,

E. a contoured control edge provided on said correcting lever and having 1. a first,steep portion,

2. a second, relatively substantially flatter portion and 3. rigid stop means at the endof said-second portion and F. camming means cooperating with said contoured controledge for causing a relatively fast rate of motion of said correcting member andthus a relatively large rate of displacement of said fuel quantity control memberwhile said camming means is in contact with said steepportion and for causing a relatively slow rate of motion of said correcting member and thus a relatively small rate of displacement of said fuel quantity control member while saidcamming means isin contactwith said flatter portion, said camming means arriving into engagement with said rigid stop means when a certain state of expansion of said temperature sensing member is reached inresponse to a predetermined temperature; the engagement. between said rigid stop means and said cammingmeans preventing further movement of said rodmeans in said first direction in'response to temperatures beyond said predetermined temperature, said first spring means undergoing compression beyond said predetermined temperature for taking up the forces generated by the expansion of said temperature sensing member subsequent to the engagement between said camming means and said rigid stop means.

2. An improvement as defined in claim 1, wherein .thetransition of said camming means from saidfirst portion of said contoured control edge to said second portion thereof occurs at a temperatureof approximately 35 C of the cooling air.

3. An improvement as defined in claim 1 wherein said predetermined temperature is approximately 80 Cv 

1. In a regulating system for controlling the fuel mixture delivered by a fuel injection system to an externally ignited, air-cooled internal combustion engine, said regulating system is of the type that includes (a) an rpm-responsive setting member, (b) a first intermediate lever to which the motions of said rpmresponsive setting member are transmitted, (c) a second intermediate lever connected to said first intermediate lever and to a fuel quantity control member to transmit thereto displacements of said rpm-responsive setting member and (d) a correcting lever to which said second intermediate lever is pivotally secured, the improvement comprising, A. an expandable temperature sensing member constituting an additional setting member and disposed within the cooling circuit of said air-cooled engine to respond to the temperatures of the cooling air, said temperature sensing member having a first end and a second end, B. rod means attached to said first end of said temperature sensing member, said rod means being displaced in a first direction by said temperature sensing member by virtue of its expansion caused by an increase in the temperature of said cooling air, C. first spring means constituting a resilient abutment for said temperature sensing member and being in engagement with said second end thereof, said first spring means opposing the expansion of said temperature sensing member, D. second spring means operatively connected to said rod means for urging the latter in a second direction opposite to said first direction; said second spring means being weaker than said first spring means for allowing said rod means to move in said first direction in response to the expansion of said temperature sensing member, E. a contoured control edge provided on said correcting lever and having
 1. a first, steep portion,
 2. a second, relatively substantially flatter portion and
 3. rigid stop means at the end of said second portion and F. camming means cooperating with said contoured control edge for causing a relatively fast rate of motion of said correcting member and thus a relatively large rate of displacement of said fuel quantity control member while said camming means is in contact with said steep portion and for causing a relatively slow rate of motion of said correcting member and thuS a relatively small rate of displacement of said fuel quantity control member while said camming means is in contact with said flatter portion, said camming means arriving into engagement with said rigid stop means when a certain state of expansion of said temperature sensing member is reached in response to a predetermined temperature; the engagement between said rigid stop means and said camming means preventing further movement of said rod means in said first direction in response to temperatures beyond said predetermined temperature, said first spring means undergoing compression beyond said predetermined temperature for taking up the forces generated by the expansion of said temperature sensing member subsequent to the engagement between said camming means and said rigid stop means.
 2. a second, relatively substantially flatter portion and
 2. An improvement as defined in claim 1, wherein the transition of said camming means from said first portion of said contoured control edge to said second portion thereof occurs at a temperature of approximately 35* C of the cooling air.
 3. An improvement as defined in claim 1, wherein said predetermined temperature is approximately 80* C.
 3. rigid stop means at the end of said second portion and F. camming means cooperating with said contoured control edge for causing a relatively fast rate of motion of said correcting member and thus a relatively large rate of displacement of said fuel quantity control member while said camming means is in contact with said steep portion and for causing a relatively slow rate of motion of said correcting member and thuS a relatively small rate of displacement of said fuel quantity control member while said camming means is in contact with said flatter portion, said camming means arriving into engagement with said rigid stop means when a certain state of expansion of said temperature sensing member is reached in response to a predetermined temperature; the engagement between said rigid stop means and said camming means preventing further movement of said rod means in said first direction in response to temperatures beyond said predetermined temperature, said first spring means undergoing compression beyond said predetermined temperature for taking up the forces generated by the expansion of said temperature sensing member subsequent to the engagement between said camming means and said rigid stop means. 